1. Field of the Invention
The present invention is directed generally to a system and method for multiplexing data transmissions and, more specifically, to a system and method for multiplexing data transmissions exchanged between a timesharing computer system and a user workstation.
2. Description of the Background of the Invention
A timesharing computer system may be accessed by a user through a video display terminal connected to the timesharing computer by means of a data communications system. The user may gain access to the timesharing computer system by establishing a program session with an application program executing on the timesharing computer. The user can interact with the application program by utilizing a keyboard attached to the video display terminal and see the results of the application on the video display terminal's screen.
Advanced video display terminals, such as distributed function terminals ("DFTs"), enable a user to initiate multiple program sessions with a timesharing computer system by establishing multiple connections between the DFT and the timesharing computer. One connection is established for each program session. The DFT utilizes windowing software to allow the user to view the multiple programs sessions simultaneously. A selection methodology permits a user to direct the keyboard input to any particular program session.
A significant drawback to the technique utilized in DFTs is that one connection must be dedicated to each program session. The number of connections on each communications pathway to the timesharing computer is usually limited and must be shared by all DFTs utilizing that communications pathway.
A type of application program called a "session manager", designed to execute on a timesharing computer system, has the capability of establishing and maintaining multiple program sessions simultaneously for a user utilizing a single video display terminal. The video display terminal maintains a single connection with the timesharing computer and establishes a single program session with the session manager program. The session manager program, in turn, maintains multiple program sessions with application programs executing on the timesharing computer system. The user can view and interact with only one program session at any given time. Using a keyboard sequence, generally known as a "hot key" sequence, the user can select from among the program sessions for viewing and keyboard input.
The disadvantage to session manager programs is that only a single application program can be viewed and interacted with at any one time. Thus, the need exists for a system which allows a user to view multiple application program sessions simultaneously, permits the user to direct keyboard input to any one of these multiple program sessions and, at the same time, establishes only a single connection with the timesharing computer system.